Welcome to the 11th Dimension - The Elegant Universe - PBS NOVA

Part 3 of "The Elegant Universe" with host Brian Greene shows how Edward Witten of Princeton's Institute for Advanced Study, aided by others, revolutionized string theory by successfully uniting the five different versions into a single theory that is cryptically named "M-theory," a development that requires a total of eleven dimensions.

Ten...eleven...who's counting? But the new 11th dimension implies that strings can come in shapes called membranes, or "branes" for short. These have truly science fiction-like qualities, since in principle they can be as large as the universe. A brane can even be a universe—a parallel universe—and we may be living on one right now.

Witten has described string theory as "a part of 21st-century physics that fell by chance into the 20th century." In fact, the theory is so far ahead of experimental technique that there is as yet no way to verify whether strings are real. But scientists at the CERN atom-smasher on the French-Swiss border are working to test of one of the predictions of string theory. This experiment may take an important step in showing that string theory is not just a crazy idea, but crazy reality. (www.youtube.com)